JPH0746771Y2 - Fuel injection pump for internal combustion engine - Google Patents

Description

Description: FIELD OF THE INVENTION The present invention relates to a cylinder liner which can be fixed in a corresponding bore of a pump casing and a pump which is driven for reciprocating work strokes and rotatable for fuel control. A plunger and a spill ring axially movable along the pump plunger for fuel control, disposed in a blind cutout integrally formed in the cylinder liner at right angles to the axis of the pump plunger. And a fuel injection pump for an internal combustion engine having at least one pump member.

In the fuel injection pump known from DE-A-3428174, the cutout is formed as an opening radially through the pump cylinder liner and is therefore no longer two lateral sides. There is only a connecting piece, and axial or radial forces are transmitted only through this comparatively weak connecting piece. In short, this type of pump cylinder liner is significantly weakened by the notches provided to receive the spill ring. Such a weakness can occur when the pump cylinder liner is tightened tightly after adjustment via screws that engage the flange of this pump cylinder liner.
Furthermore, it is particularly disadvantageous if it is axially supported in the lower part of the pump cylinder liner on the steps of the pump casing or also radially on the wall of the casing bore which receives the pump cylinder liner. Insufficient cylinder stability can lead to deformation of the cylinder liner during a firm tension, if there is already a slight axial or radial error, and thus above and below the notch. The tightly guided pump plunger is exposed to additional frictional forces in the cylinder bores that are no longer precisely aligned, which leads to premature wear and non-tightness.

In another known fuel injection pump disclosed in European Patent Publication No. 0181402, FIG. 4, the pump cylinder liner is formed in two parts and the notch when the pump is raised. It is formed by an axial hole from the upper side. Furthermore, the upper part of the cylinder liner with the flange is inserted into this hole, and a radial inlet is formed in such hole by milling. Both parts of the cylinder liner are joined together by shrink fit or hard soldering. The notch thus formed is opened laterally by milling, and the notch is suitable for an adjusting device for the spill ring, which allows the spill ring to be inserted on one side. ,
And on the other hand, it can be engaged with the spill ring for adjustment. Although such a concave shape of the notch provides relatively high stability against alignment and tension errors,
However, these parts are already aligned when the two parts of the pump cylinder liner are joined, which is laborious and expensive to manufacture. In addition, an extra work operation using an expensive tool is required, and the alignment error cannot be removed despite using the expensive tool.

The problem to be solved by the invention is to eliminate the disadvantages of the known fuel injection pumps mentioned above, so that in spite of their very simple manufacture, the alignment errors are significantly prevented. .

Means for Solving the Problem The measures of the present invention, which were devised to solve the above-mentioned problems, show that the notches extend in the working range of the spill ring parallel to each other and parallel to the pump plunger axis.
A side wall and a back wall extending at right angles to the side wall and also parallel to the pump plunger axis, wherein the back wall is provided with parallel walls. A slit-shaped through hole extending in the direction is provided, a guide device for preventing rotation of the spill ring is engaged with the through hole, and a notch is formed by cutting. To be there.

Effect of the Invention The advantage obtained by the present invention is that the wall surrounding the notch of the cylinder liner in the radial direction can receive the pressure and bending stress acting on the cylinder liner to the maximum, so that the service life of the cylinder liner is long. Is to be.
In addition, mechanical machining, such as forming the notch by cutting, can be inexpensive and is performed without the risk of strain or displacement that would lead to alignment errors.

In the field of expertise, there was a prejudice regarding the shape of pump cylinder liners. In other words, since the parts are non-axisymmetric when heat-treating the parts, the alignment error is caused by the fact that the mass is concentrated on one side. For this reason, the cylinder liner of the known fuel injection pump is also constructed in two parts. However, in the present invention, the parallel side walls can be configured such that the remaining side wall thickness is as close as possible to the spill ring, as is the case with known cylinder liners having only two supports. This results in a high stiffness and a correspondingly high moment of inertia for bending stresses caused by asymmetric drive forces.

According to a further advantageous embodiment, the transition from the parallel side wall of the notch to the back wall is stepped, the transition of the transition being in the cylindrical outer contour of the spill ring. Conforming and with such a form, the notches can be formed using an end mill as large as is allowed for the radial dimensions of the spill ring, and thus the remaining wall Can receive enough force. Furthermore, the transition section is integrally formed on the notched casing wall by an end mill. This brings the inner wall of the cutout closer to the outer peripheral surface of the spill ring, which leads to better stability.

Embodiment In the first embodiment shown in FIGS. 1 to 3, one cylinder liner 2 is shown in FIG. 1 in a pump casing 1 only partially shown of a fuel injection pump. .
A pump plunger 3 operates in a plurality of cylinder liners 2 inserted in a row in the pump casing 1 and is driven by a camshaft (not shown) for its axial movement. A cutout 4 in the form of a blind hole is provided in the cylinder liner 2, in which a spill ring 5 is axially movable along the pump plunger.

The spill ring 5 can be moved axially by an eccentric lever 6, for which the head 7 of this eccentric lever is engaged in a lateral groove 8 of the spill ring 5.

The bush 9 acts on the chamfered portion 10 of the pump plunger 3,
Moreover, since the stroke movement of the pump plunger is blocked, the pump plunger 3 can be rotated by a predetermined angle by the bush 9. The bush 9 has a gear rim in its upper section, to which a rack 11 serving as an adjusting rod engages. Of course, any other device can be used as the rotating member. The pump plunger 3 is pressed against the cam of the cam shaft via the protruding rod (not shown) via the spring 12 supported by the spring receiver 13.

The circumferential surface of the pump plunger 3 has an axially symmetric inclined groove 15
Is formed, and the upper end portion 16 of the inclined groove is opened to the vertical groove 17. The upper ends of the vertical grooves 17 are communicated with each other by a lateral hole 18 extending in the radial direction.
A blind hole 19 extending in the center of the pump plunger 3 is open, which blind hole terminates at the end face 21 of the pump plunger 3 which limits the pump working chamber 20. Side hole 18 and blind hole 19,
A connection is formed between the inclined groove 15 and the pump working chamber 20.

In the spill ring 5, two radial control holes 22 are formed, which control holes cooperate with the inclined groove 15 and the longitudinal groove 17 for defining the injection quantity. The longitudinal groove 17 has lower and upper sharp-edged control edges 24, 25 which cooperate with the lower and upper end faces 26, 27 of the spill ring 5, which also form the control edges. To do.

As can be seen from FIG. 2 in particular, the side wall 23 of the notch 4 to the back wall
A transition portion 30 to 28 is formed in a step shape. Such a stepped portion is formed during cutting by a so-called end mill, and is only required to maintain a sufficiently thick wall thickness in the cylinder liner despite the need for a space with respect to the spill ring 5. Cylinder liner 2 leaving the wall thickness
It can be made to approach the outer peripheral surface 29 of the.

In FIG. 3, the outer diameter 31 of the end mill forming the notch 4 is shown by a chain line. The curved portion 32 left when the transition from the side wall 23 of the cutout 4 to the upper and lower limiting walls 33 is not obstructed. This is because the spill ring 5 also has the curved portion.
This is because a curved portion or a bending edge having a radius of curvature corresponding to 32 is provided, or the structural height of the notch 4 is appropriately larger than the structural height and stroke required for the spill ring 5. .

In the case of the second embodiment shown in FIGS. 4 to 6, the first
A notch 104 similar to the embodiment is formed. In short, the transition 130 between the side wall 123 of the notch 104 and the back wall 128 is also rounded, i.e. formed with a bend 32, and thus is well adapted to the shape of the spill ring. The wall thickness is at least the outer peripheral surface 129 at the back wall 128 and the curved portion 32.
Is almost uniform in thickness. By eliminating the step, the spill ring, which is not shown here, is brought closer to the inner wall of the notch 104, and thus the rigidity of the cylinder liner 2 is further improved, so that the injection quantity is more perfectly balanced.

Such rounded transitions are formed either by a ball mill 34 as shown in phantom in FIGS. 4 and 5 or by casting the entire cylinder liner.

The back wall 128 of the cutout 104 is provided with a slit-shaped through hole 35 with parallel walls 36, into which the guide device of the spill ring can be engaged, and thus,
The spill ring is moved axially but is prevented from rotating.

The fuel injection pump according to the invention, which will be described with reference to FIG. 1, generally operates as follows: the UT (bottom dead center) -positioned pump plunger 3 shown in FIG. When the groove 17 is released from the spill ring 5, the fuel can flow to the pump working chamber 20 through the passage formed by the lateral hole 18 and the blind hole 19 with little squeezing.
Then, as soon as the discharge stroke of the pump plunger 3 begins, the vertical groove 17 is moved in accordance with the axial position of the spill ring 5.
Enter the spill ring 5 early or with a delay. The lower control edge 24 of the vertical groove 17 is the spill ring 5.
As soon as it passes by the lower end face 26 of the engine, the pressure necessary for the injection is built up in the pump working chamber 20 and fuel delivery to the engine, ie injection, is started. This injection is
The inclined groove 15 controls the opening of the control hole 22 of the spill ring 5 until the delivery to the engine is blocked. When the pump plunger 3 rises further, fuel flows back from the pump working chamber 20 to the suction side of the pump. After the axially defined position of the spill ring 5, the vertical groove 17 emerges from above the spill ring 5, in which case the uppermost end face 27 partially releases the vertical groove 17.

[Brief description of drawings]

1 is a partial longitudinal sectional view of a portion of a fuel injection pump having a pump cylinder liner according to the present invention, FIG. 2 is a sectional view taken along line II-II of FIG. 1, and FIG. 3 is an arrow of FIG. III
4 is a longitudinal sectional view showing only the pump cylinder seen in the direction of FIG.
FIG. 5 is a vertical sectional view showing a second embodiment of the pump cylinder liner, FIG. 5 is a sectional view taken along the line VV in FIG. 4, and FIG. 6 is a view seen in the direction of arrow VI in FIG. Is. 1 ... Pump casing, 2 ... Cylinder liner, 3 ... Pump plunger, 4 ... Notch, 5 ... Spill ring, 6 ... Eccentric lever, 7 ... Head, 8 ... Side groove, 9 ... Bush, 10 ...
Chamfer, 11 ... rack, 12 ... spring, 13 ... spring bearing, 15 ...
Inclined groove, 16 ... Upper end, 17 ... Vertical groove, 18 ... Horizontal hole, 19 ... Blind hole, 20 ... Pump work chamber, 21 ... End face, 22 ... Control hole, 23 ... Side wall, 24/25 ... Control edge, 26・ 27 ... end face, 28 ... back wall, 29
... outer peripheral surface, 30 ... transitional part, 31 ... outer diameter, 32 ... curved part, 33 ... limiting wall, 34 ... ball mill, 35 ... through hole, 36 ... wall, 104 ...
Notch, 123 ... Side wall, 128 ... Back wall, 129 ... Outer peripheral surface, 130 ... Transition section

Claims (2)

[Scope of utility model registration request] 1. A cylinder liner (2) fixable in a corresponding bore of a pump casing (1) and a pump plunger (3) driven for reciprocating work strokes and rotatable for fuel control. , Located in a blind hole notch (4, 104) integrally formed in the cylinder liner at right angles to the axis of the pump plunger and moves axially along the pump plunger (3) for fuel control In a fuel injection pump for an internal combustion engine, comprising at least one pump member, which comprises a possible spill ring (5), said notches extending parallel to one another in the working range of the spill ring (5) and a pump plunger. Two side walls (23) extending parallel to the axis and a right angle to the side walls,
Similarly, it has a back wall (28, 128) extending parallel to the pump plunger axis, and the back wall (28, 128) includes a parallel wall (36) and a slit extending in the axial direction of the pump plunger. -Like through hole (35) is provided,
A guide device for preventing the rotation of the spill ring is engaged with the through hole, and the notch (4, 10
A fuel injection pump for an internal combustion engine, wherein 4) is formed by cutting. 2. A transition portion (30) from the parallel side wall (23) of the notch (4) to the back wall (28) is formed in a step shape, and the transition of the transition portion has a spill ring (30). 5. The fuel injection pump according to claim 1, which conforms to the cylindrical outer contour of 5), and further has the transition portion integrally formed with the notched casing wall by an end mill.